Experimental verification of a new positive feedback islanding detection method for grid-connected inverter

Islanding detection is one of the most important issues for grid-connected inverter applications. A new positive-feedback anti-islanding method is presented in this paper. It utilizes the negative sequence voltage component as a positive feedback variable, and no additional negative sequence disturbance is needed at all. After islanding, the positive feedback loop will force the negative sequence voltage component away from the nominal value. A new negative sequence estimation algorithm is also presented for the successful islanding detection. Finally, the experimental tests are carried out to verify the effectiveness of the proposed method.